Tuberculosis is one of the oldest and most common infectious diseases of man. The disease is epidemic with approximately 1.8 billion people or one third of the world's population currently infected. The HIV epidemic and the emergence of multi-drug resistant M. tuberculosis (MDR-TB) has led to a critical need for the discovery and development of new and effective therapeutic agents for the treatment and control of tuberculosis. The b-sulfonylcarboxamides are a novel class of compounds which have potent in vitro activity against pathogenic mycobacteria with minimal inhibitory concentrations (MICs) ranging from 0.78 micrograms per ml to 12.5 micrograms per ml for M. tuberculosis, including MDR-TB. In addition, these compounds are highly specific for pathogenic mycobacteria, maintain activity in the presence of human serum, and are not cytotoxic for mammalian cells at 40 times their MIC for M. tuberculosis. Recent studies in our laboratories have demonstrated the antimycobacterial activity of the b-sulfonylcarboxamides to be the result of inhibition of a potentially unique pathway/target involved in central energy metabolism. The long-term objectives of this grant proposal are to determine the molecular target and mechanism of action of this novel class of compounds, with subsequent optimization of drug structure, synthesis, and preclinical drug development. This will be accomplished through: (1) characterization and identification of the target/pathway using available genomic and proteomic technologies, (2) confirmation and validation of candidate target(s) through microbiologic, biochemical, and genetic comparisons between resistant and susceptible mycobacteria, (3) determination of the three dimensional structure of the identified target, (4) design and synthesis of optimum small molecule inhibitors of the identified target/pathway (5) in vitro and in vivo toxicity and efficacy testing in a murine model of tuberculosis.